Polymer nanocomposites with a "hilly-like" SiO2/Au interlayer towards excellent high-temperature energy storage performance

Film capacitors based on polymer dielectrics are key components in pulsed power systems. But they always suffer from severe deterioration in energy storage performance at high temperatures because of accelerated carrier transfer and thermal runaway. Incorporating ceramic fillers into polymer is one of the most promising strategies to suppress the high-temperature carrier transfer. However, poor compatibility between ceramic and polymer always leads to agglomeration. Herein, SiO2 microspheres and Au nanoparticles are homogeneously embedded into the polymer films, forming a unique nanocomposite with a hilly-like SiO2/Au nanolayer. Benefiting from the wide bandgap of SiO2 microspheres and Coulomb-blockade effect of Au nanoparticles, the high-temperature charge transport is effectively suppressed. As a result, the poly(vinylidene fluoride-hexafluoropropylene) film embedded with a hilly-like SiO2/Au nanolayer exhibits significant enhancements of 252 %, 145 %, and 220 % at 50 degrees C, 80 degrees C, and 100 degrees C in energy density. It is further demonstrated that, the SiO2/Au nanolayer can also be employed to enhance the high-temperature energy performances of polyetherimide. The SiO2/Au/polyetherimide composite film achieves a high discharged energy density (6.16 J cm-3) for the eta of 80 % at 600 MV m- 1 and 150 degrees C. This work offers an innovative and effective strategy to address the long-standing filler agglomeration challenge in organic/inorganic nanocomposites, which is not only of great significance for polymer based dielectric composites, but is also illuminating for the design of other nanocomposites.